/**
 * DS4K Landing v2 — Linear × Duolingo edutech
 */
:root {
  --ds-ink: #1a2b49;
  --ds-ink-muted: #64748b;
  --ds-cream: #faf8f5;
  --ds-cream-deep: #f3efe8;
  --ds-coral: #ff6b4a;
  --ds-coral-soft: #fff0ed;
  --ds-indigo-soft: #eef2ff;
  --ds-radius: 14px;
  --ds-radius-lg: 18px;
  --ds-shadow: 0 12px 40px rgba(26, 43, 73, 0.08);
  --ds-shadow-sm: 0 4px 18px rgba(26, 43, 73, 0.06);
  /* Pastel palette — kid-friendly, low saturation */
  --pastel-peach: #ffe8dc;
  --pastel-mint: #dff8f0;
  --pastel-lavender: #ebe8ff;
  --pastel-sky: #dff0ff;
  --pastel-lemon: #fff6d6;
  --pastel-rose: #ffe4ee;
  --pastel-coral: #ffb4a2;
  --pastel-mint-mid: #a8e6cf;
  --pastel-lavender-mid: #c4b5fd;
  --pastel-sky-mid: #93c5fd;
}

@keyframes lv-drift {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(12px, -18px) scale(1.04); }
  66% { transform: translate(-10px, 10px) scale(0.97); }
}
@keyframes lv-drift-alt {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  50% { transform: translate(-16px, 14px) rotate(6deg); }
}
@keyframes lv-float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}
@keyframes lv-float-tilt {
  0%, 100% { transform: translateY(0) rotate(-2deg); }
  50% { transform: translateY(-12px) rotate(1deg); }
}
@keyframes lv-gradient-flow {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}
@keyframes lv-fade-up {
  from { opacity: 0; transform: translateY(22px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes lv-shimmer {
  0% { background-position: -200% center; }
  100% { background-position: 200% center; }
}
@keyframes lv-bar-dance {
  0%, 100% { transform: scaleY(0.55); }
  50% { transform: scaleY(1); }
}
@keyframes lv-pulse-soft {
  0%, 100% { opacity: 0.55; transform: scale(1); }
  50% { opacity: 0.85; transform: scale(1.08); }
}
@keyframes lv-twinkle {
  0%, 100% { opacity: 0.35; transform: scale(0.9) rotate(0deg); }
  50% { opacity: 0.9; transform: scale(1.1) rotate(20deg); }
}

@media (prefers-reduced-motion: reduce) {
  .lv-hero *,
  .lv-hero::before,
  .lv-hero::after,
  .lv-header,
  .lv-blob,
  .lv-shape,
  .lv-ipad,
  .lv-sheet-card,
  .lv-badge,
  .lv-hero-accent,
  .lv-ipad-bar {
    animation: none !important;
    transition: none !important;
  }
  .lv-animate-in {
    opacity: 1 !important;
    transform: none !important;
  }
}

body.landing-v2 {
  background: var(--ds-cream);
  color: var(--ds-ink);
  line-height: 1.6;
  font-family: "Pretendard", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
}

.landing-v2 .font-brand {
  font-family: "Comfortaa", "Pretendard", sans-serif;
}

/* Header */
.lv-header {
  background: linear-gradient(
    120deg,
    rgba(255, 232, 220, 0.88) 0%,
    rgba(235, 232, 255, 0.9) 45%,
    rgba(223, 240, 255, 0.88) 100%
  );
  backdrop-filter: blur(16px) saturate(1.2);
  border-bottom: 1px solid rgba(255, 255, 255, 0.65);
  box-shadow: 0 4px 24px rgba(147, 197, 253, 0.12);
  transition: box-shadow 0.3s ease;
}
.lv-header:hover {
  box-shadow: 0 6px 28px rgba(196, 181, 253, 0.18);
}
.lv-logo-icon {
  background: linear-gradient(135deg, #ffb4a2 0%, #c4b5fd 50%, #93c5fd 100%);
  background-size: 200% 200%;
  animation: lv-gradient-flow 8s ease infinite;
  box-shadow: 0 6px 18px rgba(196, 181, 253, 0.35);
}
.lv-nav-link {
  font-size: 13px;
  font-weight: 700;
  color: var(--ds-ink);
  opacity: 0.82;
  transition: color 0.2s, opacity 0.2s, transform 0.2s;
  position: relative;
}
.lv-nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--pastel-coral), var(--pastel-lavender-mid));
  transition: width 0.25s ease;
}
.lv-nav-link:hover {
  color: #7c3aed;
  opacity: 1;
  transform: translateY(-1px);
}
.lv-nav-link:hover::after {
  width: 100%;
}
.lv-btn-coral {
  background: linear-gradient(135deg, #ff8a6a 0%, #ff6b4a 55%, #ff9a7b 100%);
  background-size: 200% 200%;
  color: #fff;
  font-weight: 800;
  font-size: 13px;
  padding: 10px 18px;
  border-radius: 999px;
  box-shadow: 0 8px 22px rgba(255, 107, 74, 0.28);
  transition: transform 0.25s ease, box-shadow 0.25s ease, background-position 0.4s ease;
  animation: lv-gradient-flow 6s ease infinite;
}
.lv-btn-coral:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 14px 32px rgba(255, 107, 74, 0.38);
}

/* Hero */
.lv-hero {
  background: linear-gradient(
    145deg,
    var(--pastel-lemon) 0%,
    #fff 18%,
    var(--pastel-sky) 42%,
    var(--pastel-lavender) 68%,
    var(--pastel-peach) 100%
  );
  background-size: 300% 300%;
  animation: lv-gradient-flow 18s ease infinite;
  position: relative;
  overflow: hidden;
}
.lv-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 15% 25%, rgba(255, 180, 162, 0.35), transparent 42%),
    radial-gradient(circle at 85% 15%, rgba(196, 181, 253, 0.3), transparent 40%),
    radial-gradient(circle at 70% 80%, rgba(147, 197, 253, 0.28), transparent 38%),
    radial-gradient(circle at 25% 75%, rgba(168, 230, 207, 0.25), transparent 36%);
  pointer-events: none;
  animation: lv-drift 22s ease-in-out infinite;
}
.lv-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%231a2b49' fill-opacity='0.025'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.5;
  pointer-events: none;
}
.lv-hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
  transition: transform 0.35s ease-out;
}
.lv-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(40px);
  opacity: 0.55;
  will-change: transform;
}
.lv-blob-1 {
  width: 280px;
  height: 280px;
  top: -60px;
  right: -40px;
  background: var(--pastel-rose);
  animation: lv-drift 16s ease-in-out infinite;
}
.lv-blob-2 {
  width: 220px;
  height: 220px;
  bottom: 10%;
  left: -50px;
  background: var(--pastel-mint);
  animation: lv-drift-alt 20s ease-in-out infinite;
}
.lv-blob-3 {
  width: 180px;
  height: 180px;
  top: 35%;
  right: 20%;
  background: var(--pastel-lavender);
  animation: lv-drift 24s ease-in-out infinite reverse;
}
.lv-shape {
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  pointer-events: none;
  user-select: none;
}
.lv-shape-star {
  top: 18%;
  left: 8%;
  font-size: 1.4rem;
  color: rgba(251, 191, 36, 0.55);
  animation: lv-twinkle 4s ease-in-out infinite;
}
.lv-shape-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--pastel-coral);
  opacity: 0.5;
  top: 28%;
  right: 12%;
  animation: lv-pulse-soft 3.5s ease-in-out infinite;
}
.lv-shape-ring {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  border: 3px solid rgba(147, 197, 253, 0.45);
  bottom: 22%;
  left: 14%;
  transform: rotate(12deg);
  animation: lv-drift-alt 12s ease-in-out infinite;
}
.lv-shape-triangle {
  width: 0;
  height: 0;
  border-left: 16px solid transparent;
  border-right: 16px solid transparent;
  border-bottom: 28px solid rgba(196, 181, 253, 0.4);
  top: 12%;
  right: 28%;
  animation: lv-float 5s ease-in-out infinite;
}
.lv-hero-emoji {
  position: absolute;
  pointer-events: none;
  user-select: none;
  opacity: 0.55;
}
.lv-hero-emoji-star {
  top: -8px;
  left: -8px;
  font-size: 1.5rem;
  animation: lv-twinkle 3s ease-in-out infinite;
}
.lv-hero-emoji-num {
  top: 32px;
  right: -16px;
  font-size: 1.25rem;
  animation: lv-float 4s ease-in-out infinite 0.3s;
}
@media (max-width: 767px) {
  .lv-hero-emoji { display: none; }
}
.lv-animate-in {
  opacity: 0;
  animation: lv-fade-up 0.7s ease forwards;
}
.lv-delay-1 { animation-delay: 0.1s; }
.lv-delay-2 { animation-delay: 0.22s; }
.lv-delay-3 { animation-delay: 0.34s; }
.lv-delay-4 { animation-delay: 0.46s; }
.lv-delay-5 { animation-delay: 0.58s; }
.lv-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid rgba(255, 255, 255, 0.9);
  color: var(--ds-ink);
  font-size: 12px;
  font-weight: 800;
  padding: 8px 14px;
  border-radius: 999px;
  box-shadow: 0 4px 16px rgba(196, 181, 253, 0.2);
  backdrop-filter: blur(8px);
  position: relative;
  overflow: hidden;
}
.lv-badge::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    105deg,
    transparent 30%,
    rgba(255, 255, 255, 0.7) 50%,
    transparent 70%
  );
  background-size: 200% 100%;
  animation: lv-shimmer 4s ease-in-out infinite;
  pointer-events: none;
}
.lv-hero-title {
  font-size: clamp(2rem, 5vw, 3.15rem);
  font-weight: 900;
  line-height: 1.18;
  letter-spacing: -0.03em;
  color: var(--ds-ink);
}
.lv-hero-accent {
  background: linear-gradient(120deg, #ff6b4a 0%, #f472b6 45%, #a78bfa 100%);
  background-size: 200% auto;
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: lv-gradient-flow 5s ease infinite;
}
.lv-hero-sub {
  font-size: clamp(1rem, 2.2vw, 1.15rem);
  color: var(--ds-ink-muted);
  line-height: 1.65;
  max-width: 34rem;
}
.lv-starter-form {
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-width: 520px;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.85);
  border-radius: var(--ds-radius-lg);
  padding: 16px;
  box-shadow: 0 12px 36px rgba(147, 197, 253, 0.15);
}
.lv-starter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.lv-starter-row input,
.lv-starter-row select {
  flex: 1 1 140px;
  min-width: 0;
  border: 1.5px solid rgba(26, 43, 73, 0.12);
  border-radius: var(--ds-radius);
  padding: 14px 16px;
  font-size: 14px;
  font-weight: 600;
  background: #fff;
  color: var(--ds-ink);
}
.lv-starter-row input:focus,
.lv-starter-row select:focus {
  outline: none;
  border-color: var(--pastel-lavender-mid);
  box-shadow: 0 0 0 3px rgba(196, 181, 253, 0.25);
}
.lv-starter-row button {
  flex: 1 1 100%;
  border: none;
  cursor: pointer;
  padding: 14px 20px;
  border-radius: var(--ds-radius);
  background: linear-gradient(135deg, #ff8a6a, #ff6b4a);
  color: #fff;
  font-weight: 800;
  font-size: 14px;
  box-shadow: 0 8px 22px rgba(255, 107, 74, 0.28);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.lv-starter-row button:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(255, 107, 74, 0.35);
}
.lv-starter-row button:disabled {
  opacity: 0.6;
  cursor: wait;
}
.lv-starter-cap {
  font-size: 12px;
  color: var(--ds-ink-muted);
  font-weight: 600;
}
.lv-hero-visual {
  position: relative;
  min-height: 320px;
  z-index: 1;
}
.lv-ipad {
  width: min(100%, 300px);
  margin: 0 auto;
  background: linear-gradient(145deg, #2d3f5c, #1a2b49);
  border-radius: 24px;
  padding: 12px;
  box-shadow:
    0 20px 50px rgba(147, 197, 253, 0.25),
    0 8px 24px rgba(26, 43, 73, 0.15);
  transform: rotate(-2deg);
  animation: lv-float-tilt 5s ease-in-out infinite;
  position: relative;
  z-index: 2;
}
.lv-ipad-glow {
  position: absolute;
  inset: -20px;
  background: radial-gradient(circle, rgba(196, 181, 253, 0.35), transparent 70%);
  z-index: -1;
  animation: lv-pulse-soft 4s ease-in-out infinite;
  pointer-events: none;
}
.lv-ipad-screen {
  background: linear-gradient(145deg, #f0f4ff, #fff 40%, #e8fff8);
  border-radius: 14px;
  aspect-ratio: 4/3;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.lv-ipad-bars {
  flex: 1;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  align-items: end;
}
.lv-ipad-bar {
  border-radius: 10px;
  transform-origin: bottom center;
  animation: lv-bar-dance 2.4s ease-in-out infinite;
}
.lv-ipad-bar-1 {
  height: 48px;
  background: linear-gradient(180deg, #fde68a, #fcd34d);
  animation-delay: 0s;
}
.lv-ipad-bar-2 {
  height: 80px;
  background: linear-gradient(180deg, #fbcfe8, #f9a8d4);
  animation-delay: 0.35s;
}
.lv-ipad-bar-3 {
  height: 64px;
  background: linear-gradient(180deg, #bfdbfe, #93c5fd);
  animation-delay: 0.7s;
}
.lv-sheet-card {
  position: absolute;
  right: 0;
  bottom: 12px;
  width: 140px;
  background: rgba(255, 255, 255, 0.92);
  border-radius: var(--ds-radius);
  padding: 12px;
  box-shadow: 0 12px 32px rgba(251, 191, 36, 0.2);
  border: 1px solid rgba(255, 255, 255, 0.8);
  transform: rotate(4deg);
  animation: lv-float 4.5s ease-in-out infinite;
  animation-delay: 0.5s;
  backdrop-filter: blur(6px);
  z-index: 3;
}
.lv-sheet-card .bar {
  height: 8px;
  border-radius: 4px;
  margin-bottom: 6px;
  background: linear-gradient(90deg, #fcd34d, #f9a8d4, #93c5fd);
}

/* Sections */
.lv-section {
  padding: 72px 0;
}
.lv-section-alt {
  background: linear-gradient(180deg, #fff 0%, var(--pastel-mint) 120%);
}
.lv-section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--ds-ink);
}
.lv-section-desc {
  color: var(--ds-ink-muted);
  font-size: 15px;
  line-height: 1.65;
  max-width: 40rem;
}

/* Problem cards */
.lv-problem-grid {
  display: grid;
  gap: 16px;
}
@media (min-width: 768px) {
  .lv-problem-grid {
    grid-template-columns: 1fr 1fr;
  }
}
.lv-problem-card {
  background: #fff;
  border-radius: var(--ds-radius-lg);
  padding: 24px;
  border: 1px solid rgba(26, 43, 73, 0.08);
  box-shadow: var(--ds-shadow-sm);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.lv-problem-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--ds-shadow);
}
.lv-problem-card.is-old {
  background: linear-gradient(135deg, #f8fafc, #f1f5f9);
}
.lv-problem-card.is-new {
  background: linear-gradient(135deg, #fff 0%, var(--pastel-peach) 55%, var(--pastel-lavender) 100%);
  border-color: rgba(196, 181, 253, 0.35);
}

/* Roadmap */
.lv-roadmap {
  display: grid;
  gap: 20px;
}
@media (min-width: 1024px) {
  .lv-roadmap {
    grid-template-columns: repeat(4, 1fr);
  }
}
.lv-road-step {
  background: #fff;
  border-radius: var(--ds-radius-lg);
  padding: 22px;
  border: 1px solid rgba(26, 43, 73, 0.08);
  box-shadow: var(--ds-shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}
.lv-road-step:hover {
  transform: translateY(-5px);
  box-shadow: 0 16px 40px rgba(147, 197, 253, 0.2);
  border-color: rgba(196, 181, 253, 0.4);
}
.lv-road-num {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--pastel-sky), var(--pastel-lavender));
  color: var(--ds-ink);
  font-weight: 900;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(147, 197, 253, 0.25);
}
.lv-road-links {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: auto;
}
.lv-road-links a {
  font-size: 12px;
  font-weight: 800;
  color: var(--ds-coral);
  display: flex;
  align-items: center;
  gap: 6px;
}

/* Reviews */
.lv-review-card {
  background: rgba(255, 255, 255, 0.9);
  border-radius: var(--ds-radius-lg);
  padding: 22px;
  border: 1px solid rgba(255, 255, 255, 0.8);
  box-shadow: 0 8px 28px rgba(196, 181, 253, 0.15);
  height: 100%;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.lv-review-card:hover {
  transform: translateY(-4px) rotate(-0.5deg);
  box-shadow: 0 14px 36px rgba(251, 191, 36, 0.18);
}
.lv-stars {
  color: #f59e0b;
  letter-spacing: 2px;
  font-size: 13px;
  margin-bottom: 10px;
}

/* Interactive demo */
.lv-demo {
  background: var(--ds-ink);
  border-radius: var(--ds-radius-lg);
  padding: 24px;
  color: #fff;
}
.lv-demo canvas {
  width: 100%;
  height: 200px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  display: block;
}
.lv-demo input[type="range"] {
  width: 100%;
  margin-top: 14px;
  accent-color: var(--ds-coral);
}

/* Worksheet cards in roadmap context */
.lv-ws-grid {
  display: grid;
  gap: 14px;
}
@media (min-width: 640px) {
  .lv-ws-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 1024px) {
  .lv-ws-grid.cols-3 {
    grid-template-columns: repeat(3, 1fr);
  }
}
.lv-ws-card {
  background: #fff;
  border-radius: var(--ds-radius);
  padding: 18px;
  border: 1px solid rgba(26, 43, 73, 0.08);
  box-shadow: var(--ds-shadow-sm);
  transition: transform 0.2s, box-shadow 0.2s;
  display: block;
}
.lv-ws-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--ds-shadow);
}

/* Sticky CTA */
.lv-sticky-cta {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 45;
  background: rgba(26, 43, 73, 0.96);
  backdrop-filter: blur(10px);
  padding: 12px 16px;
  transform: translateY(110%);
  transition: transform 0.35s ease;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}
.lv-sticky-cta.is-visible {
  transform: translateY(0);
}
.lv-sticky-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  justify-content: space-between;
}
.lv-sticky-inner p {
  color: #e2e8f0;
  font-size: 13px;
  font-weight: 700;
  margin: 0;
  flex: 1 1 200px;
}
.lv-sticky-form {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  flex: 2 1 280px;
}
.lv-sticky-form input {
  flex: 1 1 140px;
  border: none;
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 13px;
}
.lv-sticky-form button {
  background: var(--ds-coral);
  color: #fff;
  border: none;
  border-radius: 10px;
  padding: 10px 16px;
  font-weight: 800;
  font-size: 12px;
  cursor: pointer;
  white-space: nowrap;
}

/* Parent guide bundle */
.lv-guide-bundle {
  background: linear-gradient(135deg, var(--ds-ink) 0%, #2d3f5c 100%);
  border-radius: var(--ds-radius-lg);
  padding: 28px;
  color: #fff;
}
.lv-guide-preview {
  background: rgba(255, 255, 255, 0.08);
  border-radius: var(--ds-radius);
  padding: 16px;
  border: 1px solid rgba(255, 255, 255, 0.12);
}

body.landing-v2 {
  padding-bottom: 80px;
}